This invention relates to unsymmetrically substituted 1,4-dioxane-2,5-diones, methods of making them, and more particularly to polymers, which polymers are either homopolymers of the unsymmetrically substituted 1,4-dioxane-2,5-diones or copolymers, and which polymers are compatible with living mammalian tissue, particularly human tissue, and which materials can be used surgically and are biologically degradable into tissue compatible components which are absorbed by living tissues. It is presently postulated that the primary degradation of the polymer is by hydrolytic fission into products which can be carried away by the living tissue and which products are degradable to excretable components or are themselves excretable. Because of the surgical demand for sutures, absorbable fabrics, gauzes, bone pins, etc. whose absorption and strength characteristics vary, it is desirable that a spectrum of strength and absorbability be provided to meet surgical demands for various procedures.